US2290501A - Ignition means - Google Patents

Description

y 1, 1942. w. J. SPENGLER ETAL 2,290,501

IGNITION MEANS Filed 001;. 26, 1939 2 Sheets-Sheet 2 I INVENTOR i'r' RNEY L 1 L Patented July 21', 1942 2,290,501

STATES PATENT OFFICE IGNrrIoN MEANS Walter]. Spengler, JakobfB. Frei, andGlen .Dingman, Sidney, N.- Y., assignors to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware a Application October 26, 1939, Serial No. 301,356

UNITED:

9 Claims. (Cl. 123-148) V v I form of circuit breaker which may be employed,

This invention relates to ignition means for internal combustion-engines and more particularly to an ignition system embodying a magneto generator as a source of electrical current.

out the present invention;

Fig. 2 is a top plan view of said magneto, part ly in section and with parts broken away;

Fig. 3 is a partial end view of said magneto,

" the view being taken substantially on lineJ-l of Fig. 1; I I

with parts of the casing removed, showing one 55 Fig. 4 is a detailed View, partly in section One of the objects of the present invention 5 and with parts broken away, showingthe disis to provide a novel low-tension distribution tributor circuitbreakers, the section being taken ignition system for use in internal combustion substantially on linel-J of Fig. 1; engines. 1 r Figs. 5 and 6 are side and end elevation views,

Another object of the invention is to provide respectively, of the distributor cam shown in seca novel magneto generator adapted for use in 10 tion in Fig. 4; and, I r

l the ignition system of an internal combustion Fig. 7 is a wiring diagram illustrating one form engine wherein low-tension distributionis emof the novel ignition distribution system comployed. prehended by the present invention.

Still another object is to provide a novel igni- A single embodiment of the invention is illustion distribution system which may be employed l5 trated, by way of example, in the accompanywithout danger of material losses or failure due ing drawings in a form adapted for use in a to flash-overs at high altitudes. six cylinder 4-str0ke cycle engine. It will be A further object is to provide a novel ignition understood, however, that the novel ignition sysdistribution system for multi-cylinder internal temandthe various novel parts thereof-comcombustion engines wherein long high-tension 0 prehended by the invention may be readily cables are eliminated thereby obviating inherent adapted for use in substantially all internal comlosses which are effected by transmission of highbustion engines employing electrical ignition tension current through long cables and minmeans irrespective of the number and arrangeimizing any fire hazard which may be occasioned ment ofthe cylinders, horse power rating or by ruptured cable insulation. speed.= Systems and apparatusembodying the A still further object is to provide a novel invention are especially adapted for use in high ignition system wherein the magneto generator speed multi-cylinder engines wherein a large requires less ventilation and may accordingly be number of sparks are required in quick succesconstructed to more effectively prevent the ension and also in aircraft engines wherein relitrance of moisture, dust and other particles of able Op r ion a hi h al itu es. an minimum foreign matter. radio interference are essentials. 2

Another object is to provide a novel ignition The source of energy f r th Pre t ignition distribution system wherein a minimum of radio ys m'i ns ed by a ovel m gneto nshielding is required to eliminate interference erator wherein only low tension current is P with radio reception in nearby receivers. duced and the distribution of current to the The above and further objects and novel feava i us engine y nd s is a mpl s d by tures of the invention will more fully appear from ns f a plurality f b r 0r Switches the following detailed description when the same ac a ed y cam m a whi h may be rotated is reh'd in connection with the accompanying at a relatively w p V l i n q ir drawings. It is to be expressly understood, how- 40 ments are thus reduced to a minimum thereby ever, that the drawings are for the purpose of p m n f a n t c nstruction which inu tration only and are not intended to define more eiiectively prevents. the entrance-21 0f dust the limits of the invention,.referencebeingpriand moisture. Additionally, the possibility of marily had for this latter purpose t th apflash-overs is entirely eliminated thus solving pended laim .I th drawings, h i 1ik '45 one of themost serious problems in high altitude reference characters refer to like parts throughflyin 1 out the several views, 7 l The illustrated embodiment of'one form. of a Fig. 1 is a side elevation, partlyin section novel magneto whi h m y be s comprises a and with parts broken away, of one novel form asing which includes a main body p rtion of magneto which may be employed in carryin a front plate II, a top cover I2 and acable out-- let adaptor B. A two pole magnetic rotor i4 is rotatably supported in the casing'by means of ball bearings I5. and I6 mounted in body l0 and front end platel I, respectively. The rotor shaft projects from the casing at the forward end thereof and may be drivably connected with the crank shaft of an engine in any suitable manner well-known in the art. A pair of stator pole shoes ll, only one of which is partially shown in Fig. l, are cast in the side walls of casing body I which cooperates with rotor H in a manner well-understood in the art to complete a magnetic circuit through the core l8 of a low tension coil l9 and thus produce an alternating low tension current in the latter when the rotor is rotated. One end of coil I9 is preferably grounded through the magneto casing and the other end is connected to the ignition system circuit in a manner to be hereinafter fully described.

Mounted on the rear or righthand end of the rotor shaft, as viewed in Fig. 1, for rotation therewith is a two-lobe cam 20 adapted to periodically open a timing circuit breaker comprising a stationary contact 2| and a movable contact 22 (Fig. 3). These contacts are adjustably mounted in a cup-shaped member 23 (Fig. 1) which is in turn mounted for angular adjustment in casing body I!) in a manner described in detail in Spengler Patent No. 2,012,290, issued August 27, 1935. As shown, a movablecontact His grounded through the magneto casing and fixed contact 2| is insulated from the ground and connected in a manner to be later described with the ungrounded end of coil IS. The specific magneto circuit breaker, above referred to, does not, per se, constitute a part' of the present invention and it is accordingly believed to be unnecessary to describe the same in more detail. "Let it be understood that various specific forms of circuit breakers may be employed in lieu of the one illustrated.

. No'vel means are provided within the magneto casing for effecting the proper distribution of current generated in coil I9 to the spark plugs in variousbylinders of an engine, saidmeans in the form illustrated comprising a circuit breaker with separable contacts for each spark plug or cylinder and a unitary cam means for actuating said circuit breakers, said cam means may consist of a cylindrical member 24 having a differential bore therethrough and'provided with circumferential and axially spaced flattened surfaces 25 milled on the periphery thereof (Figs. and 6). Cam member 24 is rotatably supported by means of ball bearings 26 and 21 on a stub shaft 28 which is in turn supported at one end in front cover plate of the magneto casing. The enlarged end of cam member 24 is provided with an external flange 29 to which is secured a spur gear 30 that meshes with a smaller gear 3| on the shaft of rotor l4. In the instant example cam 24 should be driven at one half engine crank shaft speed and the rotor shaft should be driven at one and one halftimes engine crank shaft speed. Suitable gear ratios are provided to obtain these speed ratios or any other speed ratio required in a particular engine.

Partially surrounding cam 24 is a supporting means for the distributor circuit breakers, said means including a metallic support 32 to which a plurality of breaker arms 33, together with their associated cam followers 34, and insulating plate 35 are secured by means of screws 35 and 31, respectively, plate 35 being adapted to support a plurality of stationary contact arms 38. Supporting element 32 is secured to housing I!) by any suitable means, such as screws 39 and is insulated therefrom by insulating washers 40 and sleeves 4| (Fig. 4). Movable breaker arms 33 and associated cam followers 34 may be of any suitable construction, such as illustrated and described in the above mentioned Spengler patent, and are mounted in pairs on opposite sides of supporting member 32. The cam followers of each pair engaging cam 24 at points apart and in line with one of the flattened surfaces 25.

Contact points 42 are carried by the free outer.

ends of resilient breaker arms 33 which are effective to move said points into engagement with contact points 43 mounted on stationary arms 38 when the respective cam followers 34 engage one of the flats 25 on cam 24. Brackets or arms 38 are secured to insulating plate 35 by means of terminal bolts 44 to which the inner ends of the distributing cables 45 are electrically connected. It will be seen that during each revolution of cam 24 each of the circuit breakers 42, 43 will be opened and closed once in a predetermined sequence.

The electrical connections within the magneto above-described comprise a connection 46 (Fig. 2) from one end of coil l9 to supporting member 32 through the medium of one of the fastening screws 31, said supporting member to which each of the movable contacts 42 is continuously electrically connected through one of the resilient arms 33 is also connected to stationary contact 2| of the magneto timing circuit breaker assembly and a terminal 41 by means of leads 48 and 49, respectively. A condenser 5|) which is mounted in the rear of casing body I0 is electrically grounded at one side through the casing and has the other side thereof connected by lead 5| to the terminal 41 which is likewise adapted to be connected to ground through a suitable ignition switch 52 (Fig. '1). As heretofore pointed out, the other end of coil l9, as well as movable contact 22 of the timing circuit breaker are also connected to ground as illustrated in Fig. 7.

The distribution cables 45 extend from terminals 44 through a perforated rubber grommet 53 (Fig. I) pressed between the two metallic parts comprising adaptor |3 which serves to close an opening in cover l2 and is held in position by a resilient wire bail 54 that is pivotally secured to said cover and engages laterally extending ears 55 (Fig. 2) on the adaptor. The outer ends of cables 45 are individually connected to the primary windings 56 of a plurality of transformers or ignition coils 51, only one of which'is shown diagrammatically in Fig. 7, each of said coils being mounted near a spark plug 58 which it is to serve. The secondary winding 53 of each coil 51 is connected to the center electrode of a spark plug 58 by means of a short length of cable 60 and the other terminals of the primary and secondary windings and spark plugs are grounded as indicated at El. It will be understood that each of the cables 45 connects with a different ignition coil 51 and that each of said coils serves a different spark plug.

In the operation of the illustrated apparatus and system, assuming ignition switch 52 to be in open position, rotor M is rotatably driven in the customary manner from the engine crankshaft (not shown) and cams 20 and 24 are in turn driven by the rotor. When contacts 2|, 22,

are in engagement with each other the rotation of the rotor causes a low tension current to be induced in coil I! which current follows the path of least resistance through said circuit breaker contacts 2|, 22. When this current approaches maximum value, which event occurs twice during less resistance to the flow of current than does the circuit containing one of the primary windings 55, said circuit breaker is opened by cam 20 and the induced current suddenhr rushes into the primary winding of the distributor circuit which is closed by contacts 42, 43. This rapid change or build-up of current in winding 56 causes a high tension current to be induced in secondary winding 59 and hence a spark to occur between the electrodes of spark plug 58.

After the occurrence of the spark thus generated in one of the cylinders,'contact points 2|, 22 are again permitted to engage each other and the points 42, 43 which were in engagement are then disengaged by cam 24, preferably in the order recited to avoid any possibility of a second spark occurring at spark plug 58 due to a'sudden drop in the current flow in winding 56 and to prevent the occurrence of a flash at the distributor points 42, 43. During each successive current increase in coil IS the other distributor breakers 42, 43 are closed in succession and the process is repeated until the spark plugs in all of the engine cylinders have been fired in a predetermined time sequence. This operation is repeated as long as the engine is in operation. To stop the engine, switch 52 may be closed, thereby grounding both ends of low tension coil I9.

, There is thus provided novel means for generating and distributing electrical current in the ignition system of an internal combustion engine, whereby electrical losses are reduced to a minimum and difficulty heretofore experienced with radio interference and during high altitude flying are substantially eliminated. The invention also provides a novelly combined magneto generator and current distributing means forming a unitary structure which is sturdy and com pact, yet simple, efiicient and reliable. A novel ignition system is also provided wherein the circuit breaking means transmit only low tension current and wherein the high tension conducting cables are relatively short. The system also distributes the high tension load over a plurality of ignition coils, thereby minimizing the possibility of failure in the voltage transforming means.

Although only a single embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the same is not limited thereto but that various changes which will now be obvious to those skilled in the art may be made therein. For example,

in high speed engines two magneto coils and two timing circuit breakers may be employed in a single magneto in order to reduce the number of breaks required of a single circuit breaker. Also, the distributor circuit breakers might be arranged in circumferentially spaced relation in a single plane about the periphery of a single lobe cam or the equivalent thereof. The circuit breakers may be so constructed as to be closed by the action of the cam and opened by resilient means. In some embodiments, particularly for engines having a greater number of cylinders, it may be desirable to provide a magnetic rotor and stator having a greater number of poles.

circuit through which said current normally Various other changes such as in the designand arrangement or parts illustrated may. also be made without departing from the spirit and scope of the invention. For a definition or the limits of the invention reference is had primarily to the a pended claims.

What is claimed is: 1. In an ignition, system, a magneto comprising a coil and means including a magnetic rotor for inducing low tension current in said coil, a

flows, a circuitbreaker in said circuit, cam means driven by said rotor for opening said circuit breaker whenever and only whensaid current approaches its maximum value, a condenser connected across said circuit breaker, a plurality of ignition coils, each comprising a primary winding and a secondary winding, means connecting said primary windings inparallel circuits and with said circuit breaker, saidconnecting means including a circuit breaker in series with each of said primary windings, and cam means driven by said rotor for actuating said second-named circuit breakersin a predetermined sequence, a

"different one of said second-named circuit breakers ,being in closed position each time said first- I named circuit breaker-is moved to open position,

whereby a high tension current is induced in said secondary windings in a predetermined sequence.

2. In apparatus of the class described, a casing, .a magnetic rotor journalled in said casing, a

stator comprising a plurality of pole shoes mounted in operative association with said rotor, and a low tension coil having a core magnetically connecting said pole shoes, a circuit breaker electrically connected in circuit with said coil, cam

means driven by said rotor for actuating said circuit breaker, whereby the latter is opened only when the current in said coil is at approximately its maximum value, a plurality of circuit breakers mounted in said" casing and' connected in parallel with each other and with said first-named circuit breaker, and cam means drivably connected with said rotor for normally holding said second-named circuit breakers in open position and permitting the same to close one at a time in a' predetermined sequence and at predetermined times with respect to the opening and closing of said first-named circuit breaker.

3. In a magneto having means including a magnetic rotor and a coil for generating low tension alternating current, a plurality of circuit breakers, an outgoing cable connected to a terminal of each of said circuit breakers, rotatable cam means driven by said rotor for actuating said circuit breakers whereby the latter are closed one at a time in a predetermined sequence, means connecting the other terminal of each of said circuit breakers to said coil, a single circuit breaker connected to said coil and in parallel with each of said plurality of circuit breakers, and cam means for periodically actuating said single circuit breaker.

4. In an ignition system, a source of alternating electrical current, a circuit including a cirwith each of said primary windings, and means for actuating said second-named circuit breakers,

one or said second-named circuit breakers being moved to open position and the succeeding one with said rotor, a circuit breaker for periodically interrupting the circuit containing said coil, a cam driven by said rotor for actuating said circuit breaker, a bus bar in said casing electrically connected to one contact of said circuit breaker, a plurality of circuit breakers in said casing, each having one contact thereof electrically connected to said bus :bar and the other contact thereof connected to an outgoing conductor, and cam means driven by said rotor for actuating said plurality of circuit breakers in a predetermined sequence.

6. A magneto generator comprising a casing, a magnetic rotor rotatably mounted in said casing, a stator comprising a coil operatively associated with said rotor, a circuit breaker having one contact thereof electrically connected to said coil, a cam driven by said rotor for actuating said circuit breaker to periodically interrupt the circuit containing said coil, a bus bar in said casing electrically connected with the other contact of said circuit breaker, a plurality of circuit breakers, each having one contact thereof connected I to said bus bar and the other contact thereof connected to an outgoing conductor, other cam means for actuating the said second-named circuit breakers in predetermined sequence and in timed relation to the actuation of said first-named circuit breaker, and means for connecting said bus bar to ground at the will of an operator.

7. In an ignition system for internal combustion engines, a magneto comprising a coil and means for inducing alternating current in said coil, a circuit breaker in circuit with said coil through which said current normally flows, a condenser connected across said circuit breaker, a bus bar electrically connected to one contact of said circuit breaker, a plurality of ignition coils, each comprising a primary winding and a secondary winding, means for connecting each of said primary windings to said bus bar, said means including a circuit breaker in series with each of said primary windings, means for periodically opening said first-named circuit breaker when the current in said magneto coil is at a relatively high value, and means for actuating said secondnamed circuit breakers in a predetermined sequence, a different one 01 said second-named circuit breakers being in closed position during each successive openingv of said first-named circuit breaker.

8. A magneto generator comprising a casing, a stator comprising a coil, a magnetic rotor rotatably mounted in said casing for inducing alternating current in said coil, a circuit breaker for periodically interrupting a circuit containing said coil, cam means driven by sad rotor for actuating said circuit breaker, a bus bar in said casing electrically connected to one end of said coil independently of said circuit breaker, a second cam means in said casing driven by said rotor, and a plurality of pairs of circuit breakers in said casing, the circuit breakers of each pair being disposed on opposite sides of said second cam means and operable thereby, one contact of each of said plurality of circuit breakers being mounted on and electrically connected to said bus bar and the other contact of each of said plurality of circuit breakers being connected to an outgoing conductor.

9. In apparatus of the class described, a stator comprising a coil, a magnetic rotor for inducing alternating current in said coil, a circuit breaker for periodically interrupting a circuit containing said coil, cam means for actuating said circuit breaker, a bus bar of conducting material electrically connected to said coil independently of said circuit breaker, a plurality of circuit breakers, each of the latter having one contact thereof mounted on and electrically connected to said bus bar and the other contact thereof connected to an outgoing conductor, said. plurality of circuit breakers being mounted in at least two oppositely disposed groups, and rotatable cam means mounted between said groups for actuating said plurality of circuit breakers in a predetermined sequence.

WALTER J. SPENGLER. JAKOB R. FREI. GLEN H. DINGMAN.

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